The Czechoslovakian Tatra 77 (T77) is the first serial-produced truly aerodynamically designed automobile. It was developed by Hans Ledwinka and Paul Jaray, the Zeppelin aerodynamic engineer. Launched in 1934, the Tatra 77 is a coach-built automobile constructed on a central tube-steel chassis and is powered by a 75 horsepower (56 kW) rear-mounted 3.4-liter air-cooled V8 engine. It possessed advanced engineering applications such as overhead valves, hemispherical combustion chambers, dry sump, fully independent suspension, rear swing axles and extensive use of lightweight magnesium-alloy for the engine, transmission, suspension and body. The average drag coefficient of a 1:5 model of Tatra 77 was recorded as 0.2455. The later model T77a has a top speed of over 150 km/h (93 mph) due to its advanced aerodynamics design which delivers an exceptionally low drag coefficient of 0.212,[3][4][5][6][7] although some sources claim that this is the coefficient of a 1:5 scale model, not of the car itself.[8][9]

Paul Jaray first worked at Luftschiffbau Zeppelin (LZ) where he gained experience with aerodynamic design of airships. He used his access to LZ's wind tunnels and subsequently established the streamlining principles for car design. In 1927 he founded a company specializing in developing streamlined car bodies and selling issuing licenses to major vehicle manufacturers. Tatra was the only manufacturer to incorporate Jaray streamline principles into their series car production, starting with the Tatra 77.

Before designing the large luxurious T77, Jaray designed an aerodynamic body for the Tatra 57, a mid-range model. This prototype was not further developed and failed to reach production. Instead, Jaray constructed two prototypes for a concept designated as the Tatra V570, which more closely conformed to his aerodynamic streamlining principles, featuring a beetle-shaped body.

However, at the time Tatra already had a cheap well selling car in its production range, which was moreover popular due to its continuation of simple and ultra-reliable tradition started by model Tatra 11. Although the management saw the advantages of Jaray's concept, they believed that the new model will be only an additional model with limited production, which meant that it should be aimed at the top of automobile market. The Ledwinka's team subsequently stopped work on V570 and concentrated on designing large luxurious cars. Tatra aimed at making state-of-the-art cars that would be fast, stable, nearly silent, economical and built to the most rigorous engineering standards, as well as reflect modern aerodynamic research.[11]

Hans Ledwinka was the chief-designer responsible for the development of the new car, while Erich Übelacker was responsible for the body. The development was very secretive until the last moments of the official presentation on May 3, 1934 at Prague motorshow. The car was demonstrated on the road from Prague to Karlovy Vary, where it easily reached 145 kilometres per hour (90 mph) and amazed newspapermen with great handling and comfortable ride at speeds of about 100 kilometres per hour (62 mph). That same year the T77 was presented at the Paris motorshow, where it became the center of attention not only due to its atypism, but also due to its performance. There were even demonstration rides after the ability of the car to reach 140 kilometres per hour (87 mph) with a mere 45 kilowatts (60 hp) of engine power to reach was doubted, as normally at the time for a car to reach such a speed required about twice as much horsepower. Director Maurice Elvey was so amazed by the looks of the car that he used the T77a in his science-fiction movie The Transatlantic Tunnel.[9][12]

"It is a sensation when it comes to its construction, to its appearance and to its performance. However, it isn't a sensation that would just fall down from the skies, but a logical continuation of the road, which Hans Ledwinka took thirteen years ago. The ideological principle of the new Tatra is an understanding, that the car is moving at the dividing line between the ground and the air. ... The car maintained 145km/h, it has astonishing handling, it drives through the curves with speeds that are both mad and safe, and it seems, that it is only floating on whatever road. ... It is a car, which opens new perspectives to the car construction and automotive practice."
Vilém Heinz, Motor Journal, 1934 [13]

The Tatra 77 was the particular favourite of Tatra design engineer Erich Übelacker, who owned and used a T77 himself since 1934. Other famous owners of T77s were Milos Havel, the proprietor of the film studios in Prague who bought a T77 in 1935, Austrian car designer Edmund Rumpler, who designed the aerodynamic Rumpler Tropfenwagen in 1921, Edvard Beneš, the 1930s minister of Foreign Affairs and later president of Czechoslovakia, who both owned a T77a.[15]

A number of designers around the world were trying to construct an aerodynamic car at the time, but Tatra was the first one to successfully introduce it into serial production. There were numerous reasons why Tatra designers took such a revolutionary approach to the conception of the new car: First of all it was the aim to reduce drag, mostly air-drag, which increases with the square of speed. A car with a common body shape of the era needed a very powerful engine to reach higher speeds. The Tatra's new body shape was wind tunnel tested. However, the new type of coach building required a change of the whole car's concept.

The requirement of a small front face area limited the car's height, which in turn required the use of a flat floor. That led to putting the engine in the rear of the car, directly above the driven axle. Subsequently there was no more need for a floor tunnel with a drive shaft and exhaust pipes, which contributed to weight loss. As the designers wanted to reduce the rolling resistance, they did their best to produce an engine as light as possible – an air-cooled V8 with a crank case made from elektron, a magnesium alloy. The transmission box was made from elektron as well and it was positioned in front of the rear axle and engine.

The rear position of the engine was favourable for the air cooling, while the oil cooler, battery and spare wheel were positioned in the front of the car. The frameless body was characterized by the central frame member, which was firmly welded to the floor panels and which covered the linkage to the brakes, gears, etc.

The front of the car has basically a rectangular cross section and it is rounded at the front to the height of the floor. The front bumper covers the front rounded fenders, while the lower half of the lights is embedded in the front bonnet. The rear of the car has a continuous dropping form, and it is divided by a vertical fin, which starts at the rear end of the roof and ends almost at the rear end of the car. The rear wheels have aerodynamic covers. The door handles are embedded into the door panels, from which only the door hinges stood out, if also not by much. The car had no rear window, and rear visibility was fairly limited, and only possible through slots on the sheet metal.

The first prototype of 1933 had a split windshield, while other prototypes had a one piece windshield or even one formed by three separate pieces of glass, with one large central piece and two side parts angled sharply and flowing into the sides of the body.

The air was directed to the engine by rectangular ventilation inlets behind the side windows and it left the engine compartment through the rear exit vents. At the time, Tatra registered numerous patents regarding the air flow to the rear engine compartment.

Later the rear part of the body was widened so that both the rear fenders and door hinges were embedded into the bodywork itself. The air now flowed through transversal inlets, which raised above the rear rounded roof. The trailing edge was raised.[16]

In 1935 the T77 was updated and improved, which resulted in the T77a. The capacity of the V8 was increased to 3.4 L (207 cubic inches). This accomplishment was achieved by enlarging the bore diameter from 75 to 80 mm (3.0 to 3.1 inches). The new motor increased output to 75 hp (56 kW) and maximum speed to 150 km/h (93 mph). The front now had three headlamps of which the central unit was linked to the steering on some models, making it possible to turn the lamp while steering. Some T77s and T77as were also equipped with canvas Webasto roofs. The smooth body of the T77a gave a coefficient of aerodynamic drag of 0.212, an incredibly low value even for today's cars, as only a few modern prototypes are able to achieve this figure although some sources confirm that this figure is based on a 1:5 model test.[8][9]

The Tatra 77 was a hand-built car with leather interior. Some cars had a glass partition between the front seats and the rear seats. A sliding roof was available.

An interesting feature equipped on a few of the T77 models was the steering wheel in the centre of the dashboard. The front seat passengers were seated on either side of the driver and the seats placed slightly back, as on the modern day McLaren F1. All other T77's had the steering wheel on the right hand side as Czechoslovakia, like various other European countries, drove on the left before WWII.

The unique car pictured here is the two-door coupé prototype used by Erich Übelacker. This one also had the more powerful engine from the latter Tatra 87.

Ledwinka was not entirely satisfied with the T77's handling, caused by its rather heavy rear. He started work on a successor to the T77, which was to be less heavy and with an improved weight distribution. Tatra achieved just that with the now famous Tatra 87[17] that was introduced in 1936.